1. Technical Field
An aspect of the present invention relates to a technique to convey sheets via a sheet conveying path provided for manually inserted sheets.
2. Related Art
A printing apparatus with sensors to detect a manually-inserted sheet in a sheet conveying path is known. In the printing apparatus, when a manual-insert sensor is switched on to indicate presence of a manually-inserted sheet, but an ejection sensor is not switched on to indicate presence of the sheet within a predetermined time period, it may be determined that the manually-inserted sheet is jammed in the sheet conveying path. While the manually-inserted sheet is jammed and not conveyed along the sheet conveying path, a printing operation with the manually-inserted sheet may be stopped.
Meanwhile, if the manual-insert sensor is switched on by a manually-inserted sheet, and if the manual-insert sensor is not switched off by the same manually-inserted sheet within a predetermined time period corresponding to a length of the sheet, it may be recognized that the manually-inserted sheet is inserted to reach a detective range of the manual-insert sensor while a preceding sheet is still in the detective range of the manual-insert sensor. In this regard, a tail end of the preceding sheet and a leading end of the following sheet may be undesirably in proximity to each other along the sheet conveying path. Therefore, although it may be recognized as a user's sheet-inserting error, no sheet jam is in fact occurring. Based on the recognition that the manually inserted sheets are serially conveyed without being jammed along the sheet conveying path, the printing operation with the successively inserted sheets may be continued. In other words, the printing operation may not necessary be stopped or aborted.
On the other hand, a user once inserting a sheet through a manual sheet inlet may take out the sheet from the sheet conveying path in a short time period. In such a case, while the once-inserted sheet is no longer conveyed in the sheet conveying path, it may be preferable that the printing operation is stopped. In other words, the printing operation may be stopped when an assumption that the once-inserted sheet is withdrawn is made.